The classified security alerts that are keeping Americans in a perpetual state of fear are coming under attack from federal agents who feel the warnings – some serious, some silly – are too vague to be useful.

Before Sept. 11, “we couldn’t tell anyone anything unless they had federal clearance. Now we tell them everything,” said one veteran federal agent.

“The pendulum is swinging the other way. I think we’re going overboard.”

The agent pointed to a recent Homeland Security Advisory that was sent to law-enforcement agencies across the nation on May 3. The memo quotes an unnamed Pakistani media outlet as saying Osama bin Laden plans to carry out two acts against the United States in the next four months.

The report says al Qaeda terrorists plan to target diplomats, intercity bridges, military bases, airports and radio and TV stations.

The advisory offers no assessment on the credibility of the report.

So why should law-enforcement agencies nationwide – and divers and tenants renting apartments to blow up the buildings.

Until al Qaeda hijackers slammed jets into the World Trade Center and the Pentagon, intelligence about possible terror strikes was closely held by the CIA, FBI and other agencies.

But that cloak-and-dagger secrecy came under attack after 9/11, and now terror warnings – some comical and some clearly not intended for public consumption – are openly revealed on TV.

Some federal agents oppose the new policy, believing most warnings are far too vague.

Indeed, the first three nationwide alerts contained little or no specifics.

The first, by the FBI on Oct. 11, said: “Certain information, while not specific as to target, gives the government the reason to believe that there may be additional terrorist attacks within the United States and against U.S. interests overseas over the next several days.”

In the next, on Oct. 29, the FBI warned attacks could occur “sometime this week” based on increased intelligence reports of a threat.

And on Dec. 3, Homeland Security Director Tom Ridge asked Americans to remain on high alert over the holidays – but conceded no time frame or targets were known.

Last April 24, the Bush administration made public the contents of an internal FBI memo not intended for public use that told of an unconfirmed, general threat to supermarkets or shopping centers.

Some of the warnings are comical.

In February, the FBI in Los Angeles issued a Valentine’s Day teddy-bear bomb alert after getting a tip that an Arab-looking man bought nine white teddy bears, 14 gas canisters and a dozen packs of lead gun pellets.

Proponents say the alerts keep people on their toes.

“I think they’re right in doing it,” said former New York FBI chief Lewis Schiliro. “There’s a real danger we’ll become too complacent when we really need to be more vigilant.”

Ridge believes the warnings help deter attackers.

“I think there is a firmly held belief among intelligence officials that making appropriate threats public does serve as a deterrent,” said his spokeswoman, Susan Neely.